NGC 4747
Barred spiral galaxy interacting with NGC 4725 in Coma I Group.
NGC 4747 is a barred spiral galaxy located in the constellation Coma Berenices, approximately 35 million light years from Earth. It is notable for its inclusion in the Atlas of Peculiar Galaxies in the interior absorption category and for its ongoing gravitational interaction with the neighboring spiral galaxy NGC 4725.
Quick Facts
- Epoch
- J2000
- Ra
- 12 · 51 · 45.9
- Dec
- +25 · 46 · 37
- Dist Ly
- 32 Mly (9.8 Mpc)
- Z
- 0.003969 ± 0.000003
- H Radial V
- 1,190 ± 1 km/s
- Appmag V
- 12.4
- Constellation Name
- Coma Berenices
- Notes
- tidal tail
- Names
- UGC 8005, Arp 159, CGCG 129-028, MCG +04-30-023, PGC 43586
Facts from the source article.
Lore & Background
NGC 4747 is a member of the Coma I Group, which is part of the Local Supercluster. The galaxy is interacting with the more massive spiral galaxy NGC 4725, with its spiral arms showing indications of warping. A close approach between the two galaxies occurred 320 million years before the observed epoch, creating tidal plumes in NGC 4747.
A short tidal plume extends from NGC 4747 toward NGC 4725 to the south-west, and a more pronounced plume extends towards the north-east, with a length of 8 arcminutes. The optical north-east plume has a hydrogen counterpart offset by 50 degrees from the visual counterpart. Two knots, possibly star clusters, are visible in the northeast plume; they appear to be massive enough to be self-gravitating and could become tidal dwarf galaxies.
The pair have an angular separation that corresponds to a projected linear separation of 112 kpc. The star formation rate of NGC 4747 is estimated to be 0.13 solar masses per year.
Reader's Guide
NGC 4747's significance lies in its classification as a peculiar galaxy due to interior absorption and its role as a clear example of tidal interaction between galaxies. The warped spiral arms and the presence of tidal plumes—one extending toward NGC 4725 and another more prominent northeast plume—illustrate the gravitational effects of a close encounter that occurred 320 million years before the observed state. The northeast plume is particularly noteworthy because it contains two knots that may be self-gravitating and could evolve into tidal dwarf galaxies, offering insight into galaxy formation processes. The hydrogen counterpart offset from the optical plume adds complexity to the understanding of gas dynamics in interacting systems. As a member of the Coma I Group within the Local Supercluster, NGC 4747 contributes to the study of galaxy group environments and the long-term evolution of interacting pairs. Its modest star formation rate of 0.13 solar masses per year reflects the ongoing but not extreme star formation activity triggered by the interaction.
Did You Know?
- The galaxy has a tidal plume extending 8 arcminutes to the north-east.
- Two knots in the northeast plume may become tidal dwarf galaxies.
- The pair NGC 4747 and NGC 4725 have a projected linear separation of 112 kpc.
More in Galaxy Clusters and Groups, Part 4 1-24
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